https://stackoverflow.com/questions/15483735/fatal-error-unable-to-find-local-grunt-when-running-grunt-command
npm install grunt --save-dev
or npm install 默认安装 package.json中的依赖
https://stackoverflow.com/questions/15483735/fatal-error-unable-to-find-local-grunt-when-running-grunt-command
npm install grunt --save-dev
or npm install 默认安装 package.json中的依赖